Bump firebase from 8.8.0 to 9.9.2 in /functions

Bumps [firebase](https://github.com/firebase/firebase-js-sdk) from 8.8.0 to 9.9.2.
- [Release notes](https://github.com/firebase/firebase-js-sdk/releases)
- [Changelog](https://github.com/firebase/firebase-js-sdk/blob/master/CHANGELOG.md)
- [Commits](https://github.com/firebase/firebase-js-sdk/compare/firebase@8.8.0...firebase@9.9.2)

---
updated-dependencies:
- dependency-name: firebase
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>